Four-Dimensional Greybody Factors and the Effective String.

Recently Maldacena and Strominger found that the calculation of greybody factors for {ital D}=5 black holes carrying three U(1) charges gives striking new evidence for their description as multiply wound effective strings. Here we show that a similar result holds for {ital D}=4 black holes with four U(1) charges. In this case the effective string may be thought of as the triple intersection of the 5-branes in {ital M} theory compactified on {ital T}{sup 7}. {copyright} {ital 1996 The American Physical Society.}